In conventional recoilless weapon systems, a ballast charge (ballast cartridge) is simultaneously discharged at the time of firing from the rear of the weapon, so as to counteract the recoil produced by the firing of the ammunition. Such a ballast charge is generally relatively heavy, and must be supported by a heavily built center breach. The necessary provision of such a heavy center breach adds significantly to the overall weight of the weapon.
In particular, to fire existing combat ammunition while simultaneously firing a ballast cartridge would typically require a common breach and/or a dual acting firing system. For example, two firing pins would generally be required, to simultaneously fire the ballast cartridge and the ammunition using a single trigger pull. In the event that the ballast cartridge is not fired simultaneously with the firing of the ammunition, propellant gases will escape from the base of the ballast cartridge, mitigating recoil from firing.
Thus, conventionally, recoilless weapons suffer from both undesirable overall mass, due to the need for a heavy center breach mechanism, and are fairly mechanically sophisticated, due to the need for a complicated simultaneous firing mechanism to ensure simultaneous firing. It has been found that such conventional recoilless weapons are difficult for the user to transport in battle, and that the more sophisticated the mechanism (such as the conventional firing mechanisms), the more likely misfires are to occur.